One type of image-forming device is equipped with photosensitive drums arranged in tandem and parallel to one another. Four photosensitive drums are typically provided for the four colors yellow, magenta, cyan, and black. The image-forming device also has an endless conveying belt disposed in contact with all photosensitive drums for conveying sheets of paper so that the sheets sequentially contact each of the photosensitive drums. Toner images formed on the photosensitive drums are transferred onto the sheet of paper conveyed by the conveying belt, forming a color image on the paper with the superposed images of each color.
Toner is transferred from the photosensitive drums to the conveying belt. In a conventional image-forming device, a cleaning unit is provided to remove toner from the conveying belt. The cleaning unit is provided with a waste toner accommodating unit for accommodating toner (waste toner) removed from the conveying belt.